Thread: transactions within stored procedures

Hi.

Please correct me if this is off topic for the group.  On looking
through the available postgres mailing lists, this seemed the most
appropriate for my question.

Transactions are important to my application.  I was scripting in perl
with autocommit turned off, issuing commits when appropriate.  As I
moved more of my logic into stored procedures, I looked for
documentation on how transactions work in stored procedures and I
couldn't find any!  I'm using pl/pgsql right now but would happily use
pg/perl...

By trial and error I established that a SP wraps everything it does in
one transaction, including anything from stored procedures it calls.

So here is my question:  Is there any way for me to control when
transactions are committed or rolled back within stored procedures?  Is
there an equivalent to turning autocommit off, in other words doing each
statement in its own transaction?  Or is there a command to let me
commit whenever I want to?  Also, can I roll back a transaction based on
programmatically defined logic, or only on a database error?

Thanks in advance...

--------------------->Nathan
-- 



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Nathan Young
nathan@ncyoung.com
(805) 686-2830

>
>By trial and error I established that a SP wraps everything it does in
>one transaction, including anything from stored procedures it calls.
>
>So here is my question:  Is there any way for me to control when
>transactions are committed or rolled back within stored procedures?  Is

When you invoke a procedure, this invocation is part of a transaction.
You cannot nest transactions so far, as you intend, when you want to
commit or rollback inside of a procedure.

So, when you want your procedure to fail, you would raise an exception,
otherwise, you won't. The invoking program has to react on errors, as it
should do in other situations as well.

For example, select * from xyz fails with an error, when table xyz does
not exist. If you have this statement inside of a transaction, you
would normally react on the error (commit / rollback).


Thomas Mack
TU Braunschweig, Abt. Informationssysteme